Klinefelter syndrome

Common Name(s)

Klinefelter syndrome, Klinefelter Syndrome (47, XXY)

Klinefelter syndrome is a chromosome disorder that affects a male’s physical and cognitive development. Symptoms of Klinefelter syndrome in babies may include muscle weakness; delayed ability to crawl, sit or walk (gross motor development); and delayed speech. Symptoms in boys and teenagers may include being taller than average, delayed puberty, small penis, enlarged breast tissue, weak bones, low energy levels, shyness, difficulty expressing feelings, problems with learning, and difficulty focusing. Symptoms in men may include trouble having children (infertility), small testicles and penis, being taller than average, weak bones, decreased facial and body hair, enlarged breast tissue, and decreased sex drive. Signs and symptoms of Klinefelter syndrome vary. In fact, some boys go undiagnosed until adulthood.

Typically, people have 46 chromosomes (23 pairs) in all of their cells. 22 of these pairs are similar in males and females. However one pair, called the sex chromosomes, is different in males and females. Females have two X chromosomes for their sex chromosome pair (XX), while males have an X and a Y sex chromosome pair (XY). Klinefelter syndrome is caused by extra X chromosomes in males, which is typically just one extra X (XXY), but can be more. The extra X chromosomes occur as a random event during the formation of the egg or sperm. Klinefelter syndrome is not an inherited condition.

A doctor, typically a geneticist, can see signs of Klinefelter syndrome on a physical exam by evaluating a male’s genitals and chest. The diagnosis is typically confirmed with a hormone test that shows low testosterone and a genetic test that shows one or more extra X chromosomes. Unfortunately, there is no cure for Klinefelter syndrome. Treatment consists of testosterone replacement, speech therapy, physical therapy, and fertility treatment. If you or your son have Klinefelter syndrome, talk to your doctor to discuss the best treatment plan.

Source: Advocacy organizations associated with the condition.

 

Advocacy and Support Organizations

 

Condition Specific Organizations

Following organizations serve the condition "Klinefelter syndrome" for support, advocacy or research.

Klinefelter Syndrome & Associates, Inc.

KS&A’s mission is to help individuals with one or more extra X and/or Y chromosomes and their families lead fuller and more productive lives. http://www.genetic.org/About/MissionStatement.aspx

Last Updated: 1 Nov 2014

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Unique - Understanding Chromosome Disorders

Our mission is to inform, support and alleviate the isolation of anyone affected by a rare chromosome disorder and to raise public awareness.

Last Updated: 4 Mar 2015

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AIS-DSD Support Group

The AIS-DSD Support Group is a compassionate community of individuals, families and allies collaborating to promote better lives and informed decision-making through advancement of knowledge so no one will face a diagnosis alone.

Last Updated: 12 Jan 2015

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American Association for Klinefelter Syndrome Information & Support

The mission of the American Association for Klinefelter Syndrome Information & Support is the education, support, research and understanding of 47XXY and its variants, collectively known as Klinefelter Syndrome.

Last Updated: 2 Nov 2012

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Beyond XXY, Inc.

Beyond XXY,Inc., is a U.S. nonprofit support, information, and advocacy organization. Our mission is to be a resource for the health and welfare of 47, XXYs and variants.

Last Updated: 22 Aug 2013

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Klinefelter's Syndrome Association of Canada

To support and facilitate the dissemination of information to those with Klinefelter Syndrome and their families

Last Updated: 29 Apr 2015

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The Focus Foundation

The Focus Foundation is dedicated to helping children and families affected by X & Y Variations, Dyslexia, and/or Developmental Dyspraxia. The Focus Foundation believes that through increased awareness, early identification and syndrome-specific treatment, children with these conditions can reach their full potential.

Last Updated: 31 Mar 2015

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General Support Organizations

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Advocacy and Support Organizations

 

Condition Specific Organizations

Following organizations serve the condition "Klinefelter syndrome" for support, advocacy or research.

Klinefelter Syndrome & Associates, Inc.

KS&A’s mission is to help individuals with one or more extra X and/or Y chromosomes and their families lead fuller and more productive lives. http://www.genetic.org/About/MissionStatement.aspx

http://www.genetic.org

Last Updated: 1 Nov 2014

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Unique - Understanding Chromosome Disorders

Our mission is to inform, support and alleviate the isolation of anyone affected by a rare chromosome disorder and to raise public awareness.

http://www.rarechromo.org

Last Updated: 4 Mar 2015

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AIS-DSD Support Group

The AIS-DSD Support Group is a compassionate community of individuals, families and allies collaborating to promote better lives and informed decision-making through advancement of knowledge so no one will face a diagnosis alone.

http://www.aisdsd.org

Last Updated: 12 Jan 2015

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American Association for Klinefelter Syndrome Information & Support

The mission of the American Association for Klinefelter Syndrome Information & Support is the education, support, research and understanding of 47XXY and its variants, collectively known as Klinefelter Syndrome.

http://www.aaksis.org

Last Updated: 2 Nov 2012

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Beyond XXY, Inc.

Beyond XXY,Inc., is a U.S. nonprofit support, information, and advocacy organization. Our mission is to be a resource for the health and welfare of 47, XXYs and variants.

http://xxyintersex.com/index.html

Last Updated: 22 Aug 2013

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Klinefelter's Syndrome Association of Canada

To support and facilitate the dissemination of information to those with Klinefelter Syndrome and their families

Last Updated: 29 Apr 2015

View Details
The Focus Foundation

The Focus Foundation is dedicated to helping children and families affected by X & Y Variations, Dyslexia, and/or Developmental Dyspraxia. The Focus Foundation believes that through increased awareness, early identification and syndrome-specific treatment, children with these conditions can reach their full potential.

http://www.thefocusfoundation.org/

Last Updated: 31 Mar 2015

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Scientific Literature

Articles from the PubMed Database

Research articles describe the outcome of a single study. They are the published results of original research.
The terms "Klinefelter syndrome" returned 104 free, full-text research articles on human participants. First 3 results:

Klinefelter syndrome comorbidities linked to increased X chromosome gene dosage and altered protein interactome activity.
 

Author(s): Kirstine Belling, Francesco Russo, Anders B Jensen, Marlene D Dalgaard, David Westergaard, Ewa Rajpert-De Meyts, Niels E Skakkebæk, Anders Juul, Søren Brunak

Journal: Hum. Mol. Genet.. 2017 Apr;26(7):1219-1229.

 

Klinefelter syndrome (KS) (47,XXY) is the most common male sex chromosome aneuploidy. Diagnosis and clinical supervision remain a challenge due to varying phenotypic presentation and insufficient characterization of the syndrome. Here we combine health data-driven epidemiology and ...

Last Updated: 3 Apr 2017

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Angioimmunoblastic T-Cell Lymphoma in a Patient with Klinefelter Syndrome.
 

Author(s): Yong Tae Park, Chan-Ho Park, Mi Ae Bae, Hwa Sik Jung, Youn Im Lee, Ji-Hun Lim, Hee Jeong Cha, Min Jung Seo, Seol Hoon Park, Yunsuk Choi, Hawk Kim, Jae-Cheol Jo

Journal:

 

BACKGROUND Although patients with Klinefelter syndrome have elevated risk and incidence rates for several solid cancers, reports on the incidence of hematological malignancies have been equivocal. CASE REPORT We report a patient diagnosed with angioimmunoblastic T-cell lymphoma in ...

Last Updated: 25 Jul 2016

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Human chorionic gonadotropin stimulation gives evidence of differences in testicular steroidogenesis in Klinefelter syndrome, as assessed by liquid chromatography-tandem mass spectrometry.
 

Author(s): S Belli, D Santi, E Leoni, E Dall'Olio, F Fanelli, M Mezzullo, C Pelusi, L Roli, S Tagliavini, T Trenti, A R Granata, U Pagotto, R Pasquali, V Rochira, C Carani, M Simoni

Journal: Eur. J. Endocrinol.. 2016 Jun;174(6):801-11.

 

Men with Klinefelter syndrome (KS) show hypergonadotropic hypogonadism, but the pathogenesis of hypotestosteronemia remains unclear. Testicular steroidogenesis in KS men was evaluated over three decades ago after human chorionic gonadotropin (hCG) stimulation, but inconclusive results ...

Last Updated: 18 May 2016

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Reviews from the PubMed Database

Review articles summarize what is currently known about a disease. They discuss research previously published by others.
The terms "Klinefelter syndrome" returned 23 free, full-text review articles on human participants. First 3 results:

Klinefelter syndrome (KS): genetics, clinical phenotype and hypogonadism.
 

Author(s): M Bonomi, V Rochira, D Pasquali, G Balercia, E A Jannini, A Ferlin,

Journal: J. Endocrinol. Invest.. 2017 Feb;40(2):123-134.

 

Klinefelter Syndrome (KS) is characterized by an extreme heterogeneity in its clinical and genetic presentation. The relationship between clinical phenotype and genetic background has been partially disclosed; nevertheless, physicians are aware that several aspects concerning this ...

Last Updated: 20 Sep 2016

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Mediastinal mixed germ cell tumor in an infertile male with Klinefelter syndrome:A case report and literature review.
 

Author(s): Dinesh Pradhan, Lileswar Kaman, Jasreman Dhillon, Sambit K Mohanty

Journal: J Cancer Res Ther. ;11(4):1034.

 

Klinefelter syndrome (KS) is a well-documented abnormality of the sex chromosome, with an incidence of 1 in 600 newborn males. It is characterized by a 47, XXY or a mosaic karyotype, hypergonadotrophic hypogonadism, infertility, reduced body hair, gynecomastia, and tall stature. Different ...

Last Updated: 17 Feb 2016

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Klinefelter syndrome, cardiovascular system, and thromboembolic disease: review of literature and clinical perspectives.
 

Author(s): Andrea Salzano, Michele Arcopinto, Alberto M Marra, Emanuele Bobbio, Daniela Esposito, Giacomo Accardo, Francesco Giallauria, Eduardo Bossone, Carlo Vigorito, Andrea Lenzi, Daniela Pasquali, Andrea M Isidori, Antonio Cittadini

Journal: Eur. J. Endocrinol.. 2016 Jul;175(1):R27-40.

 

Klinefelter syndrome (KS) is the most frequently occurring sex chromosomal aberration in males, with an incidence of about 1 in 500-700 newborns. Data acquired from large registry-based studies revealed an increase in mortality rates among KS patients when compared with mortality ...

Last Updated: 26 May 2016

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Clinical Trial Information This information is provided by ClinicalTrials.gov

Fertility Preservation in Cases of Klinefelter Syndrome.
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 29 May 2017

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Fertility Assessment in Patients With Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 25 Aug 2017

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Body Composition in Infants With Klinefelter Syndrome and Effects of Testosterone Treatment
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 27 Oct 2016

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